The long-term goal of this research is to understand how the brain controls and monitors the actions it produces to gain insight into the causes of dyscontrol underlying various psychopathologies. The activity of ensembles of neurons and local field potentials will be monitored in targeted layers of the frontal lobe of monkeys performing a saccade countermanding task that probes the ability to inhibit a movement at different degrees of preparation by presenting an infrequent but imperative stop signal. The frontal eye field will be studied to further elucidate the neural activity that determines whether and when a movement will occur. The supplementary eye field and anterior cingulate cortex will be studied to characterize the neural concomitants of supervisory control signals and to determine how executive control is exerted. Patterns of ensemble neural activity and laminar local field potentials will be analyzed through procedures specified by the race model of stop signal task performance to evaluate specific hypothesis about how the brain initiates and inhibits movements (Aim 1), monitors the consequences of movements (Aim 2) and exerts executive control to improve performance (Aim 3). These data will contribute to distinguishing between error, feedback and conflict monitoring theories of executive control.